Feasibility of a large area x-ray sensitive vidicon for medical fluoroscopy: Resolution and lag factors

A large area x-ray-sensitive vidicon utilizing amorphous selenium (a-Se) is being investigated as an alternative to the x-ray image intensifier and television camera combination (XRII/TV) for medical fluoroscopy. The x-ray vidicon is, to a first approximation, a scaled up version of the 1 '' (2.54 cm) light-sensitive vidicon. The modulation transfer function (MTF) of an x-ray vidicon is mainly determined by the number of lines used, the beam spot profile, and the electronic bandwidth. The x-ray vidicon is expected to have roughly the same MTF as the 1 '' vidicon from a XRII/TV system referenced to the x-ray input and as such will be superior to the MTF of the complete XRII/TV system especially in high resolution applications such as cardiac cine. Beam discharge lag is expected to be approximately the same as in the 1 '' vidicon since they have comparable photoconductor layer capacitance. Photoconductive lag is also expected to be low since a-Se is known to have a low trap density. (C) 1997 American Association of Physicists in Medicine.